Japanese published patent application No. 79/133,506 describes glasses having refractive indeces of 1.90-1.95 and similar Abbe values as described in the present invention; however, refractive values of only up to 1.95 can be achieved and these values only if a considerable amount of GeO.sub.2 is employed, which is very expensive.
Glasses having refractive values of up to 1.95 and similar Abbe indexes are also described in Japanese published patent application 79/90,218; however, these familiar glasses contain either expensive GeO.sub.2 or are not sufficiently stable towards devitrification.